Protective guard device for a transmission shaft

ABSTRACT

A protective guard device for a transmission shaft includes a tubular guard member enclosing the transmission shaft and conical guard members at the ends of the tubular member extending over the yoke arms. A radially expandible bearing member is seated in an annular groove formed in either end of the shaft or in a portion of the adjoining yoke arm. A connector interconnects the end of the tubular member to a conical guard member and the connector has a cylindrical surface therein which defines a fitting step having a diameter corresponding to the outer diameter of the bearing member when it is expanded. The bearing member when it is expanded is freely slidable over that portion of the transmission shaft assembly having the annular groove and is then contracted to be seated within the groove.

PROTECTIVE GUARD DEVICE FOR A TRANSMISSION SHAFT [75] Inventor: TheoButhe, Lohmar, Rhine,

Germany [73] Assignee: Jean Walterscheid GmbII,

Lohmar/ Rhine, Germany [22] Filed: June 11, 1974 [21] Appl. No.: 478,314

[30] Foreign Application Priority Data May 30, 1973 Germany 2327482 [52]US. Cl. 308/37; 64/3; 308/135 [51] Int. Cl. Fl6c 17/10 [58] Field ofSearch 308/37, 71, 135, 174; 64/3, 4

[56] References Cited UNITED STATES PATENTS 3,194,615 7/1965 Weasler308/37 3,531,077 9/1970 Trottier et al. 308/37 X [111 3,884,536 [451 May20, 1975 Primary Examiner-Lloyd L. King Assistant ExaminerMichael MarAttorney, Agent, or Firm-Edmund M. Jaskiewicz [57] ABSTRACT A protectiveguard device for a transmission shaft includes a tubular guard memberenclosing the transmission shaft and conical guard members at the endsof the tubular member extending over the yoke arms. A radiallyexpandible bearing member is seated in an an nular groove formed ineither end of the shaft or in a portion of the adjoining yoke arm. Aconnector interconnects the end of the tubular member to a conical guardmember and the connector has a cylindrical surface therein which definesa fitting step having a diameter corresponding to the outer diameter ofthe bearing member when it is expanded. The bearing member when it isexpanded is freely slidable over that portion of the transmission shaftassembly having the annular groove and is then contracted to be seatedwithin the groove.

8 Claims, 4 Drawing Figures 700 5 8 70b p k I III/4 I n l i 7a 6 Thepresent invention relates to a protective guard device for atransmission shaft having yoke arms at each end thereof, moreparticularly, to a connector for interconnecting each end of a tubularguard member enclosing the shaft to a respective conical guard memberextending over a yoke arm.

It has been known to enclose a transmission shaft with a protectiveguard device which comprises two telescopingly engaging tubular memberswith the guard device being supported with respect to the transmissionshaft by means of one piece slit annular bearing members seated in agroove on the shaft or on an extension of the respective yoke arm. Thebearing member is generally retained in a connector having a steppedconfiguration which functions to interconnect the tubular guard memberwith a conical guard member extending over the yoke arm and possiblyover the joint connected to the yoke arm. In one such guard device anextension of the transmission shaft is provided with an annular groovein which is seated a tubular bearing member having a plurality ofbearing segments. The segments are resilient in a radial direction tofacilitate accessibility of the joints during assembly and disassemblyof the transmission shaft and for maintenance and service purposes(German patent specification No. 1,188,869). The protective conicalguard member, the bearing member and the tubular members can be jointlyremoved in the axial direction without the use of tools. Since thetubular guard members are retained in position only by the resilientforce exerted by the bearing member segments they can be very readilyslidingly displaced from their operative positions. This characteristicis contraty to existing regulations for the prevention of accidentswhich provides that such protective guard devices must not be readilyremovable from the shaft being protected.

A further disadvantage of this protective guard device is that inremoving the guard device the bearing members are removed from theirannular grooves and are therefore susceptible to damage and in fact aredamaged in the course of frequent repeated fittings and removals. Suchdamage may affect adversely running conditions.

In another form of a protective guard device the conical or funnelshaped guard member extending over the yoke arm is made in one piecetogether with the bearing member. Bearing segments are mounted on lugsor tongues and are resilient in the radial direction. After the bearingsegments have been seated into the annular grooves, radial expansion ofthe bearing member and thus displacement of this member is prevented bya guard tube which is slid over the bearing member. (German OS 1 930278) This guard device has the disadvantage that one must first removethe guard tube and then the conical guard member with the bearingsegments in order to gain access to the yoke arms and joint members. Asin the abovementioned structure of a guard device this removal may causedamage to the bearing segments.

A further disadvantage is that since the conical member and bearingmember are made as a unit it is necessary to fabricate this structurefrom a plastic material which is suitable for a bearing function. Thisnecessity significantly increases the manufacturing cost of the entireguard device.

A further from of a protective guard device is shown in U.S. Pat. No.3,194,615 wherein a radially slit bearing member is expanded and pushedover the transmis-' sion shaft extension prior to the assembly of theguard device. The ring is intended to be seated in a correspondinglyshaped annular groove on the transmission shaft slide bearing. Theconical guard member and the tubular guard member are originallyinterconnected into a single unit and are pushed over the transmissionshaft in a direction toward the joint. This unit engages with the sidewall of the slide bearing ring member by means of a spring ring whichlimits anial displacement. The peripheral surface of the ring engageswith a corresponding cylindrically shaped inner surface of the conicalguard member. The conical guard member is provided with an opening abovethe side wall of the slide bearing ring to permit a radially resilientspring clip or washer to be inserted therethr ough. This clip or washeris supported on one side from the side wall of the slide bearing ringand on the otherside along with the opposite side wall thereof from theinner wall of the conical guard member. This construction prevents anyaxial displacment of the conical and tubular guard members.

While this protective guard device meets the requirement that such aguard device should not be readily removable, it has the disadvantagethat the radially resilient spring clip can be assembled and removedonly by a skilled workman using special tools should repairs to thejoint become necessary. It is difficult to perform such an operation atthe site where the shaft is being used which is generally inagricultural machinery.

In still another protective guard device (German Pat. No. 1,207,131) theconical guard member, the connector sleeve and the tubular guard memberare mutually locked together and pushed over a previously mounted rollerbearing which engages in the annular groove of the transmission shaft soas to be axially locked in position to the outer race ring of thisbearing. The guard device is thus axially secured and cannot be readilydetached. The bearing member with the roller bearings remains in lockedposition to offer protection to the bearing when the guard device isdisassembled. This guard device, however has the disadvantage that thebearing member together with the roller bearing must be first mountedupon the shaft before the protective guard device can be slidinglypositioned over the bearing member. Such a structure is significantlyhigher in cost since the cost of a roller bearing is greater than thatof a bearing member made of plastic material and having slide-bearingsegments. Further, after the guard device has been pushed into position,it is locked against axial displacement by fitting a tension strap.

This operation again takes time and tends to unduly complicate thestructure.

It is therefore the principal object of the present invention to providea novel and improved protective guard device for a transmission shaft.

It is another object of the present invention to provide a protectiveguard device for freely rotating transmission shafts which affordsproper protection to any persons in the vicinity of the shaft and whichcan be removed only with tools but is of a simple and strongconstruction.

It is a further object of the present invention to provide such aprotective guard device which avoids the removal of the bearing memberfrom its normal operating position in order to disassemble the guarddevice and which thereby prevents damage to the slide bearing surfaceson both the ring and the transmission shaft.

According to one aspect of the present invention the protective guarddevice for transmission shaft assembly comprising a transmission shafthaving yoke arms on the ends thereof may comprise tubular guard meansenclosing the transmission shaft. There are annular grooves in thetransmission shaft assembly at the junctures of the transmission shaftand the yoke arm. A radially expandible bearing member for each grooveis freely slidable over the portion of the transmission shaft assemblyhaving the annular groove therein when in the expanded position and whencontatcted is seated into the respective groove. Conical guard membersare provided at the ends of the tubular means extending over therespective yoke arms and are interconnected by connectors to therespective ends of the tubular means.

Each connector comprises a locking lug which is engageable with thetubular guard means. Each connector has a cylindrical surface thereinwhich defines a fitting step having a diameter approximately equal tothe outer diameter of the bearing member when in the expanded position.

The protective guard device of the present invention is so constructedthat a tubular guard member and conical guard member may be removed orassembled onto the transmission shaft in a single operation.

By providing that the bearing member is constructed initially so that inits expanded condition it engages with the inner cylindrical surface theprotective guard device consisting of the funnel guard member with thebearing member, connector and tubular guard member can be axiallyassembled in a single step or operation. The bearing member is expandedonly sufficiently to slide freely over the structure in which theannular groove is formed.

Other objects and advantages of the present invention will be apparentupon reference to the accompanying description when taken in conjunctionwith the following drawings, which are exemplary, wherein:

FIG. 1 is an elevational view partially in longitudinal section of theprotective guard device according to the present invention illustratedin the fitting or assembling position;

FIG. 2 is similar to that of FIG. 1 but showing the protective guarddevice in its operative or assembled position;

FIG. 3 is an elevational view of the connector and bearing member viewedin the direction of the line A-A; and

FIG. 4 is a plane view of the bearing member.

Proceeding next to the drawings wherein like reference symbols indicatethe same parts throughout the various views a specific embodiment of thepresent invention will be described in detail.

As may be seen in FIGS. 1 and 2, a bearing member 1 is made of asynthetic plastic bearing material and has the shape of a one-piecesliding ring having a radial cut or slit 2. Along the innercircumference of bearing member 1 are a plurality of circumferentiallyspaced bearing segments 3 which are shaped to fit closely within anannular groove 4 formed in a transmission shaft 6 to function as a slidebearing. In order to prevent axial displacement of the bearing member 1in the direction of the yoke arm 6a the end surface of the bearingmember 1 facing the yoke arm rests against a shoulder or flange 5 formedon the yoke arm 6a and extending perpendicularly to the axis of thetransmission shaft 6.

The other end surface of bearing member 1 directed toward thetransmission shaft 6 engages a surface 5a which is perpendicular to thetransmission. shaft axis and which together with flange 5 defines theannular groove 4. When the bearing member 1 is thus seated in the groove4 it is incapable of axial displacement.

The bearing member 1 is provided with an inclined surface 8 which tapersor drops in the direction toward a tubular guard member 15 whichencloses the transmission shaft 6. The inclined surface 8 permits thesliding fitting or mounting of resilient retaining lugs 9 on a connector10 during the locking operation. The tubular guard member 15 illustratedmay be only one part of a tubular guard which may consist of twotelescopingly engageable tubular members.

The connector 10 is provided with an inner cylindrical surface 10a whichdefines a fitting step and has an inclined surface 8a extendingdownwardly therefrom in the direction toward the transmission shaft 6.

The resilient retaining lugs 9 on the connector 10 have projections 11which engage in an annular groove 12 formed in the outer peripherialsurface of the bearing member 1. On the outer surface of the retaininglugs 9 there are provided reinforcement tabs 13 having slits or recesses14 at their lower ends adapted to receive a screwdriver blade for thepurpose of disengaging the retaining lugs 9 from the bearing member 1through lever action.

The connector 10 is also provided with a plurality of resilient lockinglugs 10b which engage with suitable openings in the tubular guard member15 to engage lockingly the connector 10 with the tubular guard member.

To facilitate assembly of the bearing member 1, the bearing segments 3in cross-section are provided with one end forming a radial surface 7and then extending in a curved configuration outwardly in the directiontoward the yoke arm 6a to conform to the curved section 7a of groove 4.

The bearing member 1 is fabricated so that its initial or normalposition is expanded to a diameter which corresponds to the innerdiameter of the fitting step 10a. As an alternative, the bearing membermay also be constructed so that its initial diameter corresponds to theinternal diameter of the locking lugs 10b and is maintained in itsexpanded position by a latch element provided on the inner surface ofthe fitting step 100.

In assembly, the expanded bearing member 1 is engaged firmly within thecylindrical surface 10a of the connector and then moved axially into theoperative position together with the conical guard member 16,

the connector 10 and the tubular guard member 15 without the necessityof any separate or previous assembly or fitting of the bearing member.The bearing member 1 is moved axially therewith until its end surfaceengages the shoulder 5 on the yoke arm 6a. The bearing member 1 is thenstopped from further axial movement and the continued axial movement ofthe connector 10 causes the inclined surfaces 8 and 8a to mutuallyengage and to earn the bearing member 1 inwardly until it is seated intothe groove into the position as shown in FIG. 2.Continued movement tothe left as viewed in the drawings will enable the locking lugs 9 tobecome seated in the groove 12 to retain the guard assembly in position.

Once the bearing member has been seated into the groove 4 the assemblyof the tubular guard member 15, connector and conical guard member 16may be removed axially by inserting a screwdriver blade or similar toolinto the slit l4 and disengaging the retaining lugs 9 from the bearingmember groove 12. During this operation the segments 3 of the bearingmember 1 are not removed from the annular groove and consequently theyare not susceptible to being damaged. The guard elements together withthe connector can thus be disassembled by using two screwdrivers. Nospecial tools are required nor is any particular skill or dexterityrequired on the part of the operator.

Thus it is apparent that the present invention has disclosed aprotective guard assembly for rotating transmission shafts which can bereadily assembled or disassembled with a minimum of effort and withoutthe requirement of any special tools. Further, repeated assembly orremoval of the protective guard structure will not affect adversely thebearing surfaces of the bearing member since the bearing member remainsseated in the bearing groove during subsequent assembly or disassemblyof the guard members.

It will be understood that this invention is susceptible to modificationin order to adapt it to different usages and conditions, andaccordingly, it is desired to comprehend such modifications within thisinvention as may fall within the scope of the appended claims.

What is claimed is:

1. A protective guard device for a transmission shaft assemblycomprising a transmission shaft having yoke arms on the ends thereof andcomprising tubular guard means enclosing the transmission shaft, therebeing annular grooves in said transmission shaft assembly at thejunctures of the transmission shaft and the yoke arms, a radiallyexpandible bearing member for each groove freely slidable over theportion of the transmission shaft assembly having the annular groovestherein when in the expanded position and when contracted seated intothe respective groove, conical guard members at the ends of said tubularguard means extending over the re spective yoke arms, connectorsinterconnecting said conical guard members to the respective ends ofsaid tubular guard means and each having a locking lug engageable withsaid tubular means, said connectors each having a cylindrical surfacetherein defining a fitting step having a diameter approximately equal tothe outer diameter of the bearing member when in the expanded position.

2. A protective guard device as claimed in claim 1 wherein said bearingmember has a first inclined surface and said connector has a secondinclined surface leading to the fitting step thereof, said inclinedsurfaces being mutually engageable during assembly of the protectiveguard device, said first inclined surface tapering inwardly in thedirection of said locking lug.

3. A protective guard device as claimed in claim 1 wherein each of saidbearing members having a plurality of inner circumferentially spacedbearing segments which seat into a said groove, said bearing membersbeing secured against axial movement when seated in a groove.

4. A protective guard device as claimed in claim 1 wherein there is anexternal annular groove in said bearing member, and resilient retaininglugs on each of said connectors engageable with said bearing membergrooves.

5. A protective guard device as claimed in claim 3 where each of saidbearing segments in cross-section has one end curving outwardly in thedirection of the respective yoke arm and the other end is perpendicularto the axis of the bearing member.

6. A protective guard device as claimed in claim 1 wherein the endsurface of the bearing member directed toward the respective yoke arm isperpendicular to the axis of the bearing member and engages acorresponding surface of said yoke arm.

7. A protective guard device as claimed in claim 1 wherein the bearingmember is initially in the expanded position such that its outerdiameter corresponds to the inner diameter of said fitting step.

8. A protective guard device as claimed in claim 1 wherein the bearingmember has initially an outer diameter corresponding to the innerdiameter of said locking lug, and means on said fitting step to maintainthe bearing member in the expanded position.

1. A protective guard device for a transmission shaft assemblycomprising a transmission shaft having yoke arms on the ends thereof andcomprising tubular guard means enclosing the transmission shaft, therebeing annular grooves in said transmission shaft assembly at thejunctures of the transmission shaft and the yoke arms, a radiallyexpandible bearing member for each groove freely slidable over theportion of the transmission shaft assembly having the annular groovestherein when in the expanded position and when contracted seated intothe respective groove, conical guard members at the ends of said tubularguard means extending over the respective yoke arms, connectorsinterconnecting said conical guard members to the respective ends ofsaid tubular guard means and each having a locking lug engageable withsaid tubular means, said connectors each having a cylindrical surfacetherein defining a fitting step having a diameter approximately equal tothe outer diameter of the bearing member when in the expanded position.2. A protective guard device as claimed in claim 1 wherein said bearingmember has a first inclined surface and said connector has a secondinclined surface leading to the fitting step thereof, said inclinedsurfaces being mutually engageable during assembly of the protectiveguard device, said first inclined surface tapering inwardly in thedirection of said locking lug.
 3. A protective guard device as claimedin claim 1 wherein each of said bearing members having a plurality ofinner circumferentially spaced bearing segments which seat into a saidgroove, said bearing members being secured against axial movement whenseated in a groove.
 4. A protective guard device as claimed in claim 1wherein there is an external annular groove in said bearing member, andresilient retaining lugs on each of said connectors engageable with saidbearing member grooves.
 5. A protective guard device as claimed in claim3 where each of said bearing segments in cross-section has one endcurving outwardly in the direction of the respective yoke arm and theother end is perpendicular to the axis of the bearing member.
 6. Aprotective guard device as claimed in claim 1 wherein the end surface ofthe bearing member directed toward the respective yoke arm isperpendicular to the axis of the bearing member and engages acorresponding surface of said yoke arm.
 7. A protective guard device asclaimed in claim 1 wherein the bearing member is initially in theexpanded position such that its outer diameter corresponds to the innerdiameter of said fitting step.
 8. A protective guard device as claimedin claim 1 wherein the bearing member has initially an outer diametercorresponding to the inner diameter of said locking lug, and means onsaid fitting step to maintain the bearing member in the expandedposition.